Submitted By

Nandan Kumar

2011MT0134

Guided by

Dr. A. K. Mishra

Associate Professor

Dept. of Mining Engineering

Co Guided by

Er. R. D. Dwivedi

Principal Scientist

CSRI-CIMFR

,Regional Centre,

Roorkee

Objective

Study of Classification of Rock Mass according to Q- values

RMR values

GSI values

Calculation of drill blast cycle time which includes Drilling and charging time

Ventilation time

Loading and hauling time

Scaling and rock support time

Investigation of correlations between rock mass

quality and drill blast cycle time

Outline Of Project

Literature survey

Site Selection

Design of Experiment

Field work and Data collection

Data Analysis

Result

Conclusion

Literature Survey Drill Blast Tunnelling Method

The Himalayan Tunnelling

Rock Mass Classification System

Bieniawski’s RMR Classification

Rock Tunnelling Index, Q

Geological Strength Index (GSI)

Drill-Blast Cycle

ROCK MASS RATING: RMR value : It is the geo mechanical classification developed by

Bieniawski (1973)

For application of RMR a given site should be divided into a number of geological structural units.

The following six parameters are determine for each structural unit

UCS (uniaxial Compressive Strength)

RQD (Rock Quality designation)

Joint or Discontinuity Spacing

Joint Condition

Ground Water condition and

Joint Orientation

The rating of six parameters of the

RMR system PARAMETER Assessment of values and Rating

Intact Rock UCS(MPa)

Rating

>250

15

100-250

12

50-100

7

25-50

4

1-25

1

RQD%

Rating

>90

20

75-90

17

50-75

13

25-50

8

<25

3

Mean Fracture Spacing

Rating

>2m

20

0.6-2 m

15

200-600 mm

10

50-200 mm

8

<60 mm

5

Fracture conditions

Rating

Rough tight

30

Open<1 mm

25

Weathered

20

Gouge< 5 mm

10

Gouge>5

0

Groundwater state

Rating

Dry

15

Damp

10

Wet

7

Damping

4

Flowing

0

Fracture orientation

Rating

Very favorable

0

favorable

-2

Fair

-7

Unfavorable

-15

Very unfavorable

-25

Rock Tunnelling Quality Index, Q

Where RQD = Rock Quality Designation 10 - 100

Jn = Joint set number 1 – 20

Jr = Joint roughness factor 1-4

Ja = Joint alteration and clay fillings 1 – 20

Jw = Joint water inflow or pressure 0.1– 1

SRF = stress reduction factor 1 – 20

Range: 0.0001 < Q <1000

SRF

Jw

Ja

Jr

Jn

RQDQ

GSI Hoek and Brown(1997) introduced the GSI both for hard and weak

rock masses

It is based on visual inspection of geological conditions

GSI = RMR -5 for GSI >18 or RMR > 23

= 9 ln Q’ + 44 for GSI < 18

Where Q’ = modified tunneling quality index

=

RMR = rock mass rating according to Bieniawski (1989)

Ja

Jr

Jn

RQD

GSI SHEET

Drill blast cycle

STEPS Unit Operation Time

1 Face mapping, Profile making

2 Face Drilling

3

4

Blasting

Supporting

5 Firing

6 Ventilation

7 Mucking

8 Scaling

Drill – Blast Cycle

Project Overview • Construction of a two lane 9km main

tunnel and parallel one lane escape tunnel, involving major slope cutting and embankment filling works.

• Two bridges of 40 m and 50 m span (two lanes on each bridge).

• Buildings: Two tunnel control buildings, ventilation and power buildings, administrative and maintenance building.

• MEP works: power distribution, ventilation, lighting, fire control system, video surveillance, traffic control, emergency call and communications.

• Approach roads to the Tunnel at both the ends.

Chenani Nashri Tunnel Project,

J&K

North Portal South Portal

Geometrical & Functional characteristics of CHENANI

NASHARI Tunnel Tunnel Name Chenani-Nashri

Length Approx.9000m

Type Single bore, bi-directional double lane with parallel escape tunnel, cross-

passages (pedestrian and vehicular) every 300m

Clearance traffic envelope H = 5m; W = 9.35m;

tolerance 0.05m

Lateral walkways 1.2m (W) x

2.20m (H)

Inner radius 6.65m

Min. curvature radius

300m

Max. overburden Approx.1000m

Profile Tapered with max. slope

0.5%

Excavation method as per Tender documents

D&B (NATM)

Lay-bys Every 600m staggered

Safety and fire niches on both sides

Every 150m

Underground pump rooms

No

Electrical underground substations (technical

rooms)

Every 2400m inside the cross passages

Ventilation Transverse with air ducts above road level

Typical cross section of Escape

Tunnel

Typical cross section of

MainTunnel

NATM(New austrian tunneling method)

NATM is not a method of tunneling but a strategy for tunneling which does have a considerable conformity and sequence

The basic principle of NATM are

1.mobilisation rock mass strength

2. Shotcrete protection to preserve the load carrying capacity of the rock mass

3. monitoring the deformation of the excavated rock mass

4.Providing flexible but active supports and

Correlation among rock class description as per

NATM

and behavioural categories as per Geodata

Engineering approach

Rock class description as per NATM

Qualitative approach

(Geo consult, 1993 )

Geo data Quantitative approach

(Russo & Grasso, 2007)

Class Description Geo structural condition

(typical RMR class)

A1 Stable I

A2 Slightly over breaking II

B1 Friable III

B2 Heavily friable IV

C1 Pressure

exerting/squeezing

III-IV

C2 Heavily pressure

exerting/heavily

squeezing

III-IV-V

L Loose ground/short-

term stable with low

cohesion

V

Drilling Time Data

Boomer XE3 C : Used at Main Tunnel

Drilling time : 70 Minutes ( Hole Depth : 2.5M ) Rock Class : B2 Drilling Time : 100 Minutes ( Hole Depth : 3.5M ) Rock Class : B1 Cross Section Area : 76m No. of hole : 150 Rock Bolting Time : 20 Minutes ( 9 nos. , 5.0 depth Swellex bolt ) Fixing & expansion of bolt : 15 minutes. Machine Navigation : 5-7 Minutes

E2C : Using at Escape Tunnel Drilling Time : 1:30 ( Rock Class : B1 ) Hole Depth : 4.0M Cross Section Area : 36m2 Rock Bolting Time : 15 Minutes ( 6 nos. 3.0 depth Swellex bolt )

Drill Pattern

Escape Tunnel Main

Tunnel

Jumbo

Movement

BLASTING PATTERN PARAMETER

MAIN

TUNNEL(TOP

HEADING)

ESCAPE

TUNNEL

No of Holes

Contour 30 22

Stoping 38 26

Cut 18 16+2(large hole102-

114mm)

Floor 15 6

Total no of holes 101 72

Average round

length

2.3 m 2.3 m

Total

Excavation(m3)

226.71 79.6

Total explosive(Kg) 292.88 115.4

Powder

factor(Kg/m3)

1.29 1.45

Blasting Pattern in

Main Tunnel

Blasting Pattern in Escape Tunnel

Data collection

Under this project data has been collected from Chenani

Nashri Road Tunnel, Jammu

It includes data related to geology and cycle time of different

activities of escape tunnel and main tunnel

Representation of Cycle Time

Main Tunnel Escape Tunnel

GM 4%

SUPP 40%

PROF 3%

FDT 12%

CH T 9%

VENT 3%

MUCK 18%

SCALING 11%

GM

SUPP

PROF

FDT

CH T

VENT

MUCK

SCALING

GM 4%

SUPP 37%

PROF 3%

FDT 14%

CH T 9%

VENT 2%

MUCK 20%

SCALING 11%

GM

SUPP

PROF

FDT

CH T

VENT

MUCK

SCALING

Drill Blast Cycle Time PULL

(M)

Geo

Mapping

(Min)

SUPP.

Time

(Min)

PROF

Making

(Min)

Drilling

Time

(Min)

Charging

Time

(Min)

VENT.

Time

(Min)

Mucking

Time

(Min)

Scaling

Time

(Min)

Cycle

Time

(Min)

4 20 60 15 60 40 10 130 60 395

2.9 20 60 15 60 45 15 180 60 455

3.5 30 185 15 120 75 15 240 45 725

4 30 65 15 115 60 10 170 120 585

3 25 135 40 75 60 15 165 60 575

3 30 90 30 150 75 10 275 30 690

3.5 15 90 15 70 45 25 245 30 535

3 30 60 20 100 75 10 180 60 535

4 20 120 20 130 60 10 200 30 590

4 20 45 15 90 60 10 200 30 470

Lithological Distribution of Rock Type in

Main Tunnel Siltstone,

clayey siltstone, sandy siltstone and sandstone

19%

Sandy siltstone, sandstone

and claystone

3%

Sandy siltstone,

sandstone, claystone and clayey siltstone

12%

Sandstone, claystone and

clayey siltstone 21% Sandstone,

claystone, clayey siltstone and siltstone

7%

Clayey siltstone,

sandstone and sandy siltstone

38%

Lithological Distribution of Rock Type in

Escape Tunnel

Siltstone

11%

Siltstone, intermixed

siltstone and claystone

7%

Siltstone, silty

sandstone,

sandstone 6%

Siltstone, silty

claystone, silty

sandstone, sandstone

6%

Siltstone and

Sandy siltstone

4%

Siltstone and clayey

siltstone, sandysiltstone

2%

Siltstone and clayey

siltstone, sandysiltstone

and Sandstone 20%

Sandstone, siltstone

and a thin strip of

claystone 2%

Sandstone and Siltstone

3%

silty sandstone,

sandstone

21%

Sandstone and clayey

siltstone

9% Sandstone

9%

FACE GEOTEC HNICAL DESCRIPTION ESCAPE TUNNEL

FACE GEOTECHNICAL DESCRIPTION

Main Tunnel

Rock mass quality

FROM TO Q-Value RMR GSI RQD STRENGTH Rock Class

1389.50 1392.50 1.015 47 42 45.7 48 B1

1392.50 1395.10 2.45 46 40 49 45 B1

1395.10 1397.00 2.3 44 40 46 45 B1

1397.00 1399.50 1.015 47 42 45.7 47.5 B1

1399.50 1402.50 2.3 44 40 46 45 B1

1402.50 1405.00 1.08 44 42 49 45 B1

1405.00 1408.00 2.6 50 40 52 45 B1

1408.00 1410.00 1.235 49 45 56 55 B1

1410.00 1412.50 1.235 49 45 55.6 55 B1

1412.50 1415.00 2.6 49 40 52 45 B1

1415.00 1417.70 1.01 46 40 45.7 45 B1

1417.70 1421.00 2.6 48 40 52 45 B1

1421.00 1423.50 0.76 46 40 45.7 45 B1

Ro

ck m

ass Q

ua

lity in

Ma

in

tun

ne

l

00

.5 11.5 22.5 33.5 44

.5 5

1389.50

1408.00

1426.00

1446.50

1465.50

1484.50

1563.20

1577.30

1591.30

1604.50

1625.80

1650.50

Ch

ain

ag

e N

o v

s Q

valu

es

0 10 20 30

40 50

60

1389.50

1408.00

1426.00

1446.50

1465.50

1484.50

1563.20

1577.30

1591.30

1604.50

1625.80

1650.50

Ch

ain

ag

e n

o. v

s RM

R

Va

lue

s

05

101520253035404550

138

9.5

0

140

8.0

0

1426

.00

144

6.5

0

146

5.50

148

4.5

0

156

3.20

1577

.30

159

1.30

160

4.5

0

1625

.80

1650

.50

GSI Values in Main

Tunnel Rock Mass

Quality

Range

Q Values 0.52 to 2.6

RMR Values 42 to 51

GSI Values 35 to 45

Rock mass Quality in Escape

tunnel

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

216

4.6

219

1.5

2219

.5

224

4

2372

.70

240

8.2

0

244

0.8

0

249

1.5

2533

.2

256

5

2657

.5

Chainage No vs Q values

0

10

20

30

40

50

60

216

4.6

219

1.5

2219

.5

224

4

2372

.70

240

8.2

0

244

0.8

0

249

1.5

2533

.2

256

5

2657

.5

Chainage No Vs RMR Values

0

10

20

30

40

50

60

216

4.6

219

1.5

2219

.5

224

4

2372

.70

240

8.2

0

244

0.8

0

249

1.5

2533

.2

256

5

2657

.5

Chainage No. Vs GSI values Rock Mass

Quality Range

Q Values 1.90 to 4.13

RMR Values 47 to 53

GSI Values 42 to 50

Correlation of data (Main

Tunnel) Correlation between

Cycle time and Q-value in main tunnel

y = -0.3841Q2 + 1.48 Q + 4.73

R² = 0.44

5.0

5.4

5.8

6.2

6.6

0 0.5 1 1.5 2 2.5 3

T0

.33

Q

Main Tunnel Correlation between

Cycle time and RMR-value in main tunnel

CT0.33 = -0.0182(RMR)2 + 1.84(RMR) - 39.9

R² = 0.72

4

5

6

7

42 44 46 48 50 52

T0

.33

RMR

Main Tunnel Correlation between

Cycle time and GSI-value in main tunnel

CT0.33 = 1.13(GSI)0.45

R² = 0.86

4.50

5.00

5.50

6.00

6.50

7.00

30 35 40 45 50

T0

.33

GSI

Correlation of data (Escape

Tunnel) Cycle time vs Q values

(Q < 6)

Cycle time vs Q values (Q>6)

y = -0.0203x + 2.9136 R² = 0.7724

2.72

2.76

2.80

2.84

2.88

2.92

0 2 4 6 8

T0

.2

Q2

y = 0.0131x + 2.5654 R² = 0.9147

2.60

2.64

2.68

2.72

2.76

2.80

0 5 10 15 20

T0

.2

Q2

Correlation of data (Escape

Tunnel) Cycle time vs RMR values

(RMR <49 )

Cycle time vs RMR values (RMR > 49)

CT = 3.305(RMR)2 - 316.5(RMR) + 7750

R² = 0.73

140

160

180

200

220

240

44 45 46 47 48 49

Cy

cle

tim

e p

er m

etre

pu

ll

RMR

CT = 0.216(RMR)3 - 35.36(RMR)2 + 1927(RMR)-

34825

R² = 0.96

100

120

140

160

180

47 49 51 53 55 57

Cy

cle

tim

e p

er m

etre

pu

ll

RMR

Correlation of data (Escape

Tunnel) Cycle time vs GSI value(GSI< 43)

Cycle time Vs GSI value(GSI > 43)

CT = 1.292(GSI)2 - 111(GSI) + 2526

R² = 0.70

100

140

180

220

260

34 36 38 40 42 44

Cycl

e ti

me

per

m p

ull

GSI

CT = -0.246(GSI)2 + 25.76(GSI)- 507.56

R² = 0.89

100

120

140

160

180

30 40 50 60

Cycl

e ti

me

per

pu

ll

GSI

Conclusion From the undertaken study conclusion may be as follows:

1.The change in Rock mass quality direct influence on cycle time of Tunnel which has

been true for both the tunnel(Main & Escape Tunnel).

2.In case of Main Tunnel(Diameter 14.02 m) Cycle time is directly proportional to

Rock mass quality upto a certain range and after that range the cycle time becomes

constant.

3. In case of escape tunnels (diameter 6.55 m), the cycle time is inversely proportional

to rock mass quality

It may be due to change in degree of fragmentation, which influenced the dig rate

as for the lower value of rock mass quality (Q<2.45,RMR values <48.6 and GSI

values < 43 ) degree of fragmentation was good whereas for higher values of rock

mass quality i.e. (Q >√6,RMR >48.6 and GSI >43) the degree of fragmentation

was bad. The specific charge was same for all cases.

Contd……

4. This indicates that the specific charge , design and

sequence need to be changed with change in rock

mass quality to suite the excavator and achieve the

desire efficiency.

5.From the undertaken study it may be concluded that for

varying rock mass quality specific charge, design and

sequence need to be change to keep the same face

advancement and the efficiency of excavation.

Thank You